A while ago I asked about using thoneysuckle hedge shoots (Amur honeysuckle, not the viny type) as arrows.
Report: I found the wood seasoned well in 3 months indoors and can be heat straightened well. The pith is small in diameter. The wood has almost no visible grain. My initial success has been with naturally tapered shafts running from 5/16 at the nock end to 7/16 at the point end, with 3/8" hex nuts screwed onto the tapered tip and duct tape "Seminole" fletching. I just wanted to see what spine etc worked. I shot them from 3 bows ranging from 45 to 52 pounds pull and they shot well and are strong too. I think these would hold up really well.
If you have hedges near you look for upright shoots coming off the main stem of the bush, and choose ones thicker than you think you need. They do shrink some on seasoning. This could be an abundant source for shoot arrows.
My willow shoots of the same diameter shrunk too much and have weak spine.
Some dogwood shoots and branches I found appear to be excellent for spine and strength but I have not shot them yet.
Thick goldenrod shafts I collected turned out to be very weak in spine and I did not bother to try to shoot them, as I was afraid they would break. I think that over 35#, these would flex badly unless the bow was center shooting.
Horseweed or mare's tail has good spine and is very light but does not look strong enough for long life. Anyone have luck with these lasting? I do not want to invest a lot of work if arrows will shatter. I expect to have to make hardwood nocks and foreshafts for these.